Edwin t



(No Model?) E n E. T. GREENFIELD. METAL COVERED ELBOW. Y 151055117276.:Patented Mar. 27, 1894.

Nrrs @rares ATENT OFFICE.

METAL-COVERED ELBOW.

SPECIFICATION forming part of Letters Patent No. 517,276, dated March27', 1894.

Application filed July 14,1891. Serial No. 399,470. (No model.)

To otZZ whom t may concern:

Be it known that I, EDWIN T. GREENFIELD, acitizen of the United States,residing at New York, county and State of New York, have made a new anduseful Invention in Compound Tubular Elbows, of which the following is aspecification.

My invention is directed particularly to a novel form of compound elbowdesigned especially for use in connection with electrical conduits, andto this end it is constructed of insulating material surrounded by ametal sleeve or tube, both of said parts being bent into the form of anelbow in a manner hereinafter described.

My invention will be fully understood by referring to the accompanyingdrawin gs taken in connection with the following specification.

Figure 1, is a vertical sectional View of the preferred formV ofapparatus used in making my improved elbow and illustrating also such anelbow in process of construction. Fig. 2, is a plan View as seen lookingat Fig. 1,from the top toward the bottom of the drawing, while Fig. 3 isa plan View of my improved form of compound elbow. A

Referring now to the drawings in detail, A represents a pair ofstandards or supports secured to a table, bench or other stationary'support not shown. To the upper end of these supports is secured bybolts b a grooved forming block B, made preferably of metal and havingon its upper surface a groove G of the diameter of the piping or tubingfrom which it is desired to construct the elbows. The operative portionof this groove G is provided with a series of lateral grooves g gdesigned to form corrugations c on the inner side of the completed elbowas shown in Fig. 3.

H is a lever pivotally secured to one side of the forming block B with aforming roller R having a groove G of the same diameter as the groove G.

D is a sliding locking block having a loop or eye at its upper end asclearly shown in Fig- 2, of substantially the same diameter as theexterior diameter of the tube C, from which it is desired to form theelbow. This sliding block D is secured to a vertically sustained rod Eand held normally in a position slightly above the face ot' the groove Gby a spiral spring S.

T represents a short section of tube made preferably of paper oranalogous fibrous material and impregnated with insulating material in amanner well understood by those skilled in the art of preparing conduittubes,

and C is a tube of brass, copper or analogous' metal which fits snuglyabout the paper tube T.

M is a mandrel made of soft rubber, leather or analogous yieldingmaterial adapted to iit tightly in the interior of the tube T.

The method of operation by which my improved elbows are formed with theabove de# scribed mechanism is as follows: Short straight sections ofthe described metal covered tubing are Iirst heated in boiling water orin any other manner preferred, the heating being for the purpose ofpreventing the cracking or checking of the outer portion of the papertube during the process of constructing the` elbow. One end of the shorttube is then inserted in the eye of the locking block D, said eyeprojecting slightly above the face of the groove G under pressure of thespring S. The mandrel M, of soft rubber, leather or other yieldingmaterial is then covered with soap stone or some material which willpermit of its ready withdrawal and is forced through the tube T. ThehandlelH is then drawn in the direction shown by the arrow in Fig. 1,from the position indicated in dotted lines to that indicated in fulllines. During the first operation of the stroke of this operatinghandle, the eye and locking block D are forced into the position shownand caused to hold the tube securely as it is bent over the formingblock B during the progress of the roller R to its nal position shown infull lines. The compound tube, therefore, assumes, when completed, theconformation shown in Fig. 3, of a completed elbow, the corrugations cbeing formed by the lateral grooves g in the groove G of the formingblock B. The handle H and forming roller R are returned to their rstposition and the elbow is withdrawn from the locking block D, afterwhich the mandrel M is removed, the completed elbow being ready for saleand use.

I am aware that heretofore pipe elbows have been constructed consistingof cast iron having a vitreous lining with a lling between the vitreouslining andthe metal as disclosed in patent to E. H. Austin, No. 209,103,granted IOO October 22, 1878, and I make no claim herein broad enough toinclude such a structure, my invention being directed to an elbow madeof an insulating tube, surrounded by a thin metallic jacket or sleeve,which partakes of the curved conformation of the insulating tube when itis bent or formed, and in my preferred form of elbow the metallic jacketor sleeve is corrugated on its inner curve in order to give greaterstrength thereto, and to aid in retaining the curved insulating tube inits bent or curved shape after the elbow is completed.

Having thus described my invention, what I claim. and desire to secureby Letters Pateut of the United States, is-

1. An elbow made of insulating material and a close fitting surroundingmetallic jacket or sleeve.

2. An elbow made of non-corrosive material and surrounded by a closefitting metallic jacket or sleeve.

3. An elbow made of a bent metallic tube which iucloses an insulatingtube, the two being rmly united together, substantially as described.

4. Au elbow made of an insulating tube surrounded-by a thin metallicjacket or sleeve corrugated on its inner curve and adapted to hold theinsulating tube in its curved position, substantially as described.

5. A curved elbow made of concentric tubing, the inner tube being ofinsulating material, the outer tube of metal and corrugated on the innercurve of the elbow, substantially as described.

6. A curved elbow made of concentric tubing the inner tube beine; offibrous material saturated with an insulating compound, and the outertube of metal having lateral corrugations on the inner curve of theelbow,sub stantially as described.

7. A curved elbow composed of concentric tubes T and C, the inner tube Cbeing of pa.- per treated with an insulating material, and the outertube of metal and corrugated on the inner curve of the elbow,substantially as described.

EDWIN T. GREENFIELD. Witnesses:

C. J. KINTNER, M. L. BUTLER.

